Direct access storage devices (DASD) have become part of everyday life, and as such, expectations and demands continually increase for greater speed for manipulating and for holding larger amounts of data. To meet these demands for increased performance, the mechano-electrical assembly in a DASD device, specifically the Hard Disk Drive (HDD) has evolved to meet these demands.
Advances in magnetic recording heads as well as the disk media have allowed more data to be stored on a disk's recording surface. The ability of an HDD to access this data quickly is largely a function of the performance of the mechanical components of the HDD. Once this data is accessed, the ability of an HDD to read and write this data quickly is primarily a function of the electrical components of the HDD.
A computer storage system may include a magnetic hard disk(s) or drive(s) within an outer housing or base containing a spindle motor assembly having a central drive hub that rotates the disk. An actuator includes a plurality of parallel actuator arms in the form of a comb that is movably or pivotally mounted to the base about a pivot assembly. A controller is also mounted to the base for selectively moving the comb of arms relative to the disk.
Each actuator arm has extending from it at least one cantilevered electrical lead suspension. A magnetic read/write transducer or head is mounted on a slider and secured to a flexure that is flexibly mounted to each suspension. The read/write heads magnetically read data from and/or magnetically write data to the disk. The level of integration called the head gimbal assembly (HGA) is the head and the slider, which are mounted on the suspension. The slider is usually bonded to the end of the suspension.
A suspension has a spring-like quality, which biases or presses the air-bearing surface of the slider against the disk to cause the slider to fly at a precise distance from the disk. Movement of the actuator by the controller causes the head gimbal assemblies to move along radial arcs across tracks on the disk until the heads settle on their set target tracks. The head gimbal assemblies operate in and move in unison with one another or use multiple independent actuators wherein the arms can move independently of one another.
To allow more data to be stored on the surface of the disk, more data tracks must be stored more closely together. The quantity of data tracks recorded on the surface of the disk is determined partly by how well the read/write head on the slider can be positioned and made stable over a desired data track. Vibration or unwanted relative motion between the slider and surface of disk will affect the quantity of data recorded on the surface of the disk.
To mitigate unwanted relative motion between the slider and the surface of the disk, HDD manufacturers are beginning to configure HDDs with a secondary actuator in close proximity to the slider. A secondary actuator of this nature is generally referred to as a microactuator because it typically has a very small actuation stroke length, typically plus and minus 1 micron. A microactuator typically allows faster response to relative motion between the slider and the surface of the disk as opposed to moving the entire structure of actuator assembly.